Chakra failed when build with std:c++latest by msvc on Windows

Chakra failed when build with std:c++latest by msvc on Windows. Could you please help take a look at this?

**You can repro this issue as the steps below:**

1. git clone -c core.autocrlf=true https://github.com/microsoft/ChakraCore D:\Chakra\src
2. open a clean VS2019 x86 prompt and browse to D:\Chakra\src
3. set CL=/std:c++latest
4. msbuild /m /p:Platform=x86 /p:Configuration=Test /p:WindowsTargetPlatformVersion=10.0.18362.0 Build\Chakra.Core.sln /t:Rebuild

**Failures:**
JsrtContextCore.i
JsrtContextCore.i(1558483): error C2220: the following warning is treated as an error
JsrtContextCore.i(1558483): warning C4499: 'static': an explicit specialization cannot have a storage class (ignored)
JsrtContextCore.i(1558485): warning C4499: 'static an explicit specialization cannot have a storage class (ignored)
JsrtContextCore.i(1558487): warning C4499: 'static': an explicit specialization cannot have a storage class (ignored)